prerm is in mkvtoolnix 6.7.0-1.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 | #! /bin/sh
set -e
[ "$1" = "remove" ] || [ "$1" = "deconfigure" ] && \
update-alternatives --remove mkvinfo /usr/bin/mkvinfo-text
exit 0
|